Predators drive community reorganization during experimental range shifts

1. Increased global temperatures caused by climate change are causing species to shift their ranges and colonize new sites, creating novel assemblages that have historically not interacted. Species interactions play a central role in the response of ecosystems to climate change, but the role of trophic interactions in facilitating or preventing range expansions are largely unknown.

2. The goal of our study was to understand how predators influence the ability of range-shifting prey to successfully establish in newly available habitat following climate warming. We hypothesized that fish predation facilitates the establishment of colonizing zooplankton populations, because fish preferentially consume larger species that would otherwise competitively exclude smaller bodied colonists.

3. We conducted a mesocosm experiment with zooplankton communities and their fish predators from lakes of the Sierra Nevada Mountains in California, USA. We tested the effect of fish predation on the est...